객관식
Given that the molar mass of NH_3 is 17.03 g/mol, how many moles of NH_3 are present in a 107.1 g sample?
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2. Atoms & Elements
Calculating Molar Mass
객관식
Acetic acid has the chemical formula CH3COOH. How many grams of hydrogen (H) are present in 1.52 grams of acetic acid?
A
0.152 grams
B
0.304 grams
C
0.456 grams
D
0.192 grams
검증된 단계별 안내1
Determine the molar mass of acetic acid (CH3COOH) by summing the atomic masses of all atoms in the formula: carbon (C), hydrogen (H), and oxygen (O). Use the atomic masses approximately as C = 12.01 g/mol, H = 1.008 g/mol, and O = 16.00 g/mol.
Calculate the total mass of hydrogen atoms in one mole of acetic acid. Since there are 4 hydrogen atoms in CH3COOH, multiply the number of hydrogen atoms by the atomic mass of hydrogen: \(4 \times 1.008\) g/mol.
Find the mass fraction of hydrogen in acetic acid by dividing the total mass of hydrogen atoms by the molar mass of acetic acid: \(\text{mass fraction of H} = \frac{\text{mass of H in 1 mole}}{\text{molar mass of acetic acid}}\).
Multiply the mass fraction of hydrogen by the given mass of acetic acid (1.52 g) to find the mass of hydrogen present: \(\text{mass of H} = \text{mass fraction of H} \times 1.52\) g.
The result from the previous step gives the grams of hydrogen in 1.52 grams of acetic acid.
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